Records of the Geological Survey of India. 
6 
[VOL. X. 
lapped. For a full account of these important observations I may refer to Mr. Blanford’s 
paper in the current number of the Records. 
The observations just noted have supplied a knowledge of the western margin of a well- 
defined but little explored geological region—that of which the Arvali hills (or mountains) 
form the best-known geographical feature, stretching to the south-south-west into Guzerat, 
and passing on the north north-east under the Indo-Gangetic plains, about their water-shed, 
and touching the Jamna at Delhi. The eastern limits of the region are very well marked 
by the scarp at the Viiulhyans, stretching from near Agra to Chittorgarh and Neemuch, and 
thence bj’ the scarp of the Malwa plateau formed of the Deccan trap. The Arvali region is 
believed to be formed entirely of gneissic aud transition rocks, the remains of an exceedingly 
ancient mountain system, or area of special disturbance; even the Vindhyan formation exhi¬ 
bits little disturbance within its confines. For some seasons past Mr. Hacket has been 
engaged upon these rocks in the north. Last year he carried his lines as far as Jaipur. 
The isolated condition of the outcrops, in detached ridges and hills separated by wide 
plains of sand or of alluviun, makes it very difficult to discover the normal order of succes¬ 
sion of the several groups of rocks, all being without a trace of fossil remains. Our difficulty 
here at present is the occurrence, within a moderately large area, of several strong rock-groups, 
having much mutual resemblance, and each independently in natural contact with a funda¬ 
mental gneiss. 
Mr. Willson was also engaged upon the older rocks, having completed the mapping of 
the Bijawar formation in Bundelkund, with a large adjoining area of overlying lower and 
upper Vindhyans, and of the underlying gneiss. 
Mr. Wynne did not return from furlough till the end of the field season. He has since 
done important work in the Museum in arranging the Kach and Salt Range collections. 
For the first time since the institution of the Survey the annual report has to record the 
retirement upon pension of any of the staff. Dr. Oldham resigned the post of Superin¬ 
tendent in April, after a tenure of 25 years. The work done up to date will form a permanent 
record of the value of his services. Mr. Tween retired in September, after a service of 15 
years, for the greater part of which time he had zealously performed the duties of Chemist to 
the Survey. In both cases, failing health made the step unavoidable. The loss we have thus 
sustained is the more felt, since it is determined that, for the present at least, the number 
of our staff cannot be restored to its full strength. 
Publications .—Of the Memoirs of the Geological Survey of India, Volume XII 
was issued during the past year. Part 1 is the result of several seasons’ work by Mr. 
R. Bruce Foote, and includes a very large area in the South Mahratta Country, where 
several basins of our azoic formations occur between the great spread of the Deccan trap 
on the north and the gneiss forming the whole middle area of the peninsula to the 
south. The small skeleton-map attached to the Memoir does very poor justice to the accuracy 
and detail of Mr. Foote’s work, the whole of which is ready for publication on the Indian 
Atlas sheets, as soon as a plan can be matured for the regular issue of our work in that 
form. Part 2 is Mr. Mallet's report on the coal-fields of Upper Assam. It will be a very 
useful guide in the practical exploration of that field. 
Volume XIII was fully passed for press before the close of the year. Part 1, containing 
Mr. Hughes’ memoir and maps of the Wardha valley coal-fields, will be issued before the 
